Properly processed and stored, monochrome (e.g. Black and White silver halide) film continues to meet both legal and archival standards for the long term storage of information. This has in fact buoyed its continued use despite competition from digital imaging technologies such as magnetic and optical storage over the last decade. It is clear that monochrome silver halide film will continue to serve a vital role in the archival storage of information. Its human readable form is especially important in its acceptance since it immunizes it against digital format obsolescence which threatens to be the bane of digital storage techniques.
However, because monochrome film only yields monochromatic information on output, typical single channel recording methods lose all color information content of the original document. This problem is easily, but inconveniently, solved in the existing art with monochrome films by resorting to classical three channel separation techniques. This involves the recording of the original image onto monochrome film through three separate color filters, nominally red(R), green(G) and blue(B), thus arriving at three distinct and disjoined image frames or field-of-views (FOV); one for each color. For example, see U.S. Pat. No. 3,589,811 issued Jun. 29, 1971 which discloses the use of crossed beam splitters in a camera for recording three color separation images on a monochrome film.
A reconstructed image with color information can then be retrieved from these three records by reversing the process, with special attention paid to spatial registration of the records. Because each frame is separate and disjoined from members of its triad, the reconstruction process can become cumbersome due to handling and alignment issues.
U.S. Pat. No. 4,926,250 issued May 15, 1990 to Konishi discloses a color image recording and reproducing apparatus using monochromatic recording medium. The separate frames are optically recorded on microfilm and a blip mark adjacent each frame is recorded to indicate the color of the separation. The blip marks are employed in reproduction apparatus to select the color of the toner or paper, but no attempt is made to register multiple color separations in the output apparatus.
Existing film scanning apparatus is configured to scan a single image in a single optical field of view (FOV). The necessity of scanning three color separations to reproduce a color image recorded on a monochromatic film in the conventional manner reduces the productivity of such scanning apparatus by a factor of three.
It is also well known in the art that there is less visible information in the red and blue separations than in the green separation. Thus, a method that employs the same amount of recording medium for the red, blue and green separations is inefficient.
There exists a need therefore for an improved method of recording a color image on a monochromatic recording medium.